Water pollution caused by industrial wastewater including a large amount of oil and oil spilled from a ship has had disastrous effects on the ecosystem, and an enormous amount of economic cost and time is required to restore polluted areas. For this reason, a technology for separating water and oil in wastewater and oil spilled on the sea has been suggested.
As conventional technologies of separating water and oil, an adsorption method and a gravity separation method are known. The adsorption method is a method of selectively absorbing oil only with an adsorbent. This method is limited in the amount of oil to be removed at once, and additional costs and secondary environmental pollution may be caused by treating the adsorbent absorbing oil.
The gravity separation method is a method of removing oil floating on water using a gravity difference between the water and the oil, and does not use consumables such as an adsorbent, resulting in a reduction in costs. However, this method has low efficiency in separating oil, and the separated oil includes lots of water, which makes it difficult to recycle the separated oil.